Glass furnace and process.



P. L. T. HROULT.

GLASS FURNAGE AND PROCESS.

APPLIGATION FILED AUG. 26, 1910.

1,069,255. Patented Aug. 5, 1913.

INVENTOR WITNESSES:

wrm/e 5w. @MAMA-f l rAnL L. '.tf. HRO'ULT,

or LA PRAZ, FRANCE.

GLASS FURNACE AN' PROCESS.

Specification of Letters Patent.

Application fue-a. August 26.1910. serial No. 579,136. Y

To all whom #may concern Be it known that lf., PAUL LOUIS Tous- SAINT HROULT, a citizen of the Republic of France, res1ding yat La Savoie, France, have invented certain: new and useful Improvements in Glass Furnaces and Processes, of which; the following is a specifica-tion.

Inthe manufacture of glass, difficulty is experienced i-nl the use ot. the ordina-ry reverbcratory furnace in keeping the moltep glass suliiciently fluid. Glass being a pyroconductor,lor body which is electro-conductive when heatedi tofusion, but a non-conductor when solid and cold, it would appear feasible and'" desirable to utilize the electric furnace by passing'a' current through the bath of molten glass, which with a suticient current would thus be kept molten, since any fall in temperature would occasion such an increased resistance as to re heat the mass to fluidity. A difficulty- Will be encountered, however, in that the. glassl is an electrolyte, and the ellfect, even of an alternating current, Would' be to a'lt'er its composition by the' reduction of the metallic oxids which are essential ingredientsof the glass, this reduction taking place at and near the carbon terminals ofthe furnace.

The present invention provides an electric furnace which overcomes this objection and 'enables the electric heating of molten glass to be practically accomplished. The bath of molten glass is made the resistant andf heat-generating conductor; massive carbon;= terminals are appliedto lead the current to"- and froml opposite ortions of the bath.; and to prevent any re uction due to contact of the glass with the carbon, intervening electrodes of molten metal are provided, a metal being chosen for this purpose which is elec-l tro-negative to the metals in the glass; Copper is a suitable and desirable metal forthis purpose. l The accompanying drawing shows in transverse section a' suitable construction of glass furnace embodying this invention. I Referring to the drawing, let A designate a suitable hearth, which may be of brick or fire-brick, and B a suitable support there for; C C are cast iron-or other suitable casings for the carbon terminals, D D, the

latter being made of carbon or graphite which is molded or packed into these casings. Connection may be made with a dynamo or other electric generator E by suitgraphite.

- jects over these casing's andV over the carbon terminals, as shown.

G isa usual form of arch constituting' within' it ai ladling cha-mber H out of which th'e hot glass may be ladl-ed through a' suit- PatentetiAug. 5,191 3. 1

able door in front. The opposite abutments of the arch project down as submerged partitions into the bat-'h of Huid glass. This baith is designated at J, and the mixture of' glass-forming material as it is fed to the furnace is shown at K K, this mixture not yet having become molten.

L L are electrodes of copper' or other metal which is electro-negative to the Inet-ils inthe glu-ss, and Which must of course bel of greater specific gravity than the glass itselfl so as to underlie it; and separate it yfrom the carbon termin-als D D. f

The current used may be either direct or alternating, the latter being preferable.

The currentinust of course be of sufficient,"

volume so that in opposing the resistance of the Ina-ss of fluid glass Ji. it Will generate Sufiicient heat to keep this bath of glass molten. lt is tofbev observed that the metal terminals o1' electrodes L L are Widely separated-sous to'interpose between them a con:-

sifleralbl'e length of the resistant conductor constituted bythe molten glass, so as to enable-a current of practicable electro-motive force to be used.

In operation, sulicient copperis placed upon the 'carbons D D to form When molten p the pools L L. A starting path for the current is provided by placing graphite over the brick heart-h A, which may be done either by `suitably connecting one or more graphite pencils, or by providing an'elongatedpile of powdered or granulated ,Y

Y This starting path is indicated b y the dotted line M. Or a copper rod might beapplied at the outset, which would fuse and join the pools L L. A sutlicent quantity of glass or of the glass mixture K is then provided to form a. molten pool of glass, being so applied as not to disturb the graphite starting path. The current 1s then started and meetlng. the resistance of the' graphite M, it heats this to incandescence and fuses the surrounding glass, forming a pool, which then conducts its proportion of the current, and which. may be added to from time to time until a sufficient mass has been fused and is kept heated to the desired iuidity. The small quantity of graphite used for starting soon disappears, Aand the glass aloneconducts the current.

. The ladling chamber H is located ap.

proximately midway between the electrodes L L,l and hence should present an intermediate potential so nearly neutral that there would be little liability of the workman receiving a shock while ladling out the glass. But to fully guard against such shock, it is preferable to ground the middle portion of theafurnace, which may readily be done by introducing a metal rod P, preferably f iro-n or steel, into the brick hearth A., so that it.-

projects into electric contact with the bath J, and forms a conductor connecting it electrically with the cast iron base B or otherwise with the ground. The workman may stand onVY an insulating platform, or on an iron platform which is also grounded or Iconnected electrically with the rod P, so

as to present the same potential as the middle of the bath, and hence the same as that of the glass in the chamber H. Y

En place of copper for the electrodes L lL. nickel, iron, or other suitable metal may be used.

It is important that the c-arbonvconductors I DID be of large section, and therefore of ample conductivity, so that practically no heat is generated in these conductors: 'llhese carbon conductors are of low heat conductivity.

By my furnace it is practicable, by suitably proportioning the parts, to interpose the greatest resistance in the hath of glass nace with a current between electrodes consisting of pools of molten metal electrovnegative to the metals of the glass.

3. An electric furnace ,for treating glass adapted to contain a bath of molten glass',

and having opposite terminals of metal elec- 'tro-negative'to the metals of the glass.

4. An electric furnace for treating glass adapted to contain a hath of molten glass, and having opposite terminals of molten metal electro-negativeto the metals of the glass.

5. ln an electric furnace, a non-conduct! ing hearth and inclosing walls for holding a.

bath of molten glass, with carbon terminals on opposite sides of said hearth, and a 'molten metal electrode overlying each, of said carbons.

v6. A glass furnace adapted tohold a'bath of molten glass, 'and having opposite electrodes, and an intervening ladling space,

with a ground connection to'the molten glass adjacent to said ladling space, to protect the workman from shocks.

- lin Witness whereof, ll have hereuntov Signed my name in the presence of two subfscribing Witnesses.-

PAUL L. T. HRUULT.

Witnesses:

ARTHUR C. FRASER, FRED WHITE. 

